Отправка данных контактной формы

[DellXT]

В контактной форме есть несколько текстовых полей и несколько дропдаунов с возможностью выбрать несколько значений. Вопрос в том, как эти значения отправить по электронной почте? Текстовые значения типа string по одному слову отправляются отлично. Но как отправить массивы в которых входит несколько значений? Как их собрать методом $_POST и выложить в письме? Помогите пожалуйста!

форма:

<section class="post-content-area pt-20">
    <div class="container">
        <div class="row">
            <div class="col-lg-8 posts-list">
                <div class="card card-signin my-5">
                    <div class="card-body">
                        <h5 class="card-title text-center" style="font-size: 26px">Test contact form</h5>
                        <form method="post" action="email-script.php" enctype="multipart/form-data" id="emailForm"> 
                            <div class="form-group">
                                <input type="text" name="name" id="name" class="form-control" placeholder="Name" >
                                <div id="nameError" style="color: red;font-size: 14px;display: none">nameError</div>
                            </div>
                            <div class="form-group">
                                <input type="text" name="surname" id="surname" class="form-control" placeholder="Surame" >
                                <div id="nameError" style="color: red;font-size: 14px;display: none">nameError</div>
                            </div>
                            <div class="form-group">
                                <input type="text" name="phone" id="phone" class="form-control"  placeholder="Phone" >
                                <div id="subjectError" style="color: red;font-size: 14px;display: none">subjectError</div>
                            </div>
    <div class="form-group">
     <label>First Level Category</label><br />
     <select id="first_level" name="first_level[]" multiple class="form-control">
     <?php
     foreach($result as $row)
     {
      echo '<option value="'.$row["first_level_category_id"].'">'.$row["first_level_category_name"].'</option>';
     }
     ?>
     </select>
    </div>
    <div class="form-group">
     <label>Second Level Category</label><br />
     <select id="second_level" name="second_level[]" multiple class="form-control">
 
     </select>
    </div>
    <div class="form-group">
     <label>Third Level Category</label><br />
     <select id="third_level" name="third_level[]" multiple class="form-control">
 
     </select>
    </div>
        <div class="form-group">
                                <input type="file" name="attachment" id="attachment" class="form-control">
                                <div id="attachmentError" style="color: red;font-size: 14px;display: none">attachmentError</div>
                            </div>
                            <div class="submit">
                                <center><input type="submit" name="submit" onclick="return validateEmailSendForm();" class="btn btn-success" value="SUBMIT"></center>
                            </div>
                        </form>
                    </div>
                </div>
            </div>
        </div>
    </div>
</section>

емайл-скрипт:

<?php

if(isset($_POST['submit'])){
    // Get the submitted form data
    $name = $_POST['name'];
    $surname = $_POST['surname'];
    $phone = $_POST['phone'];
    $date = $date = date('Y-m-d H:i:s');
    $uploadStatus = 1;
 
    // Upload attachment file
    if(!empty($_FILES["attachment"]["name"])){
 
        // File path config
        $targetDir = "uploads/";
        $fileName = basename($_FILES["attachment"]["name"]);
        $targetFilePath = $targetDir . $fileName;
        $fileType = pathinfo($targetFilePath,PATHINFO_EXTENSION);
 
        // Allow certain file formats
        $allowTypes = array('pdf', 'doc', 'docx', 'jpg', 'png', 'jpeg');
        if(in_array($fileType, $allowTypes)){
            // Upload file to the server
            if(move_uploaded_file($_FILES["attachment"]["tmp_name"], $targetFilePath)){
                $uploadedFile = $targetFilePath;
            }else{
                $uploadStatus = 0;
                $statusMsg = "Sorry, there was an error uploading your file.";
            }
        }else{
            $uploadStatus = 0;
            $statusMsg = 'Sorry, only PDF, DOC, JPG, JPEG, & PNG files are allowed to upload.';
        }
    }
 
    if($uploadStatus == 1){
        // Recipient
        $toEmail = 'gmail@gmail.com';
        // Sender
        $from = 'test@test.com';
        $fromName = $name . ' ' . $surname;
        // Subject
        $emailSubject = 'Test mail';
        // Message
        $htmlContent ='$name . ' ' . $surname . ' '. $phone . ' ' . $date;';
 
        // Header for sender info
        $headers = "From: $fromName"." <".$from.">";
 
        if(!empty($uploadedFile) && file_exists($uploadedFile)){
            // Boundary
            $semi_rand = md5(time());
            $mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";
            // Headers for attachment
            $headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$mime_boundary}\"";
            // Multipart boundary
            $message = "--{$mime_boundary}\n" . "Content-Type: text/html; charset=\"UTF-8\"\n" .
                "Content-Transfer-Encoding: 7bit\n\n" . $htmlContent . "\n\n";
            // Preparing attachment
            if(is_file($uploadedFile)){
                $message .= "--{$mime_boundary}\n";
                $fp =    @fopen($uploadedFile,"rb");
                $data =  @fread($fp,filesize($uploadedFile));
                @fclose($fp);
                $data = chunk_split(base64_encode($data));
                $message .= "Content-Type: application/octet-stream; name=\"".basename($uploadedFile)."\"\n" .
                    "Content-Description: ".basename($uploadedFile)."\n" .
                    "Content-Disposition: attachment;\n" . " filename=\"".basename($uploadedFile)."\"; size=".filesize($uploadedFile).";\n" .
                    "Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
            }
            $message .= "--{$mime_boundary}--";
            $returnpath = "-f" . $phone;
            // Send email
            $mail = mail($toEmail, $emailSubject, $message, $headers, $returnpath);
            // Delete attachment file from the server
            @unlink($uploadedFile);
        }else{
            // Set content-type header for sending HTML email
            $headers .= "\r\n". "MIME-Version: 1.0";
            $headers .= "\r\n". "Content-type:text/html;charset=UTF-8";
            // Send email
            $mail = mail($toEmail, $emailSubject, $htmlContent, $headers);
        }
 
        // If mail sent
        if($mail){
            $statusMsg = 'Your email attachment request has been submitted successfully !';
        }else{
            $statusMsg = 'Your request submission failed, please try again.';
        }
    }
    echo '<script>alert("'.$statusMsg.'");window.location.href="./";</script>';
}
 
?>